Determination of Potassium, Sodium, and Total Alkalies in Portland Cement, Fly Ash, Admixtures, and Water of Concrete by a Simple Flow Injection Flame Photometric System

A simple flow injection with flame photometric detection has been developed for determination of sodium, potassium, and total alkalies in portland cement, fly ash, admixtures, and water of concrete. A liquid sample or a digest of solid sample was injected into a water carrier stream which flowed to a flame photometer. A change in emission intensity at a selected wavelength was recorded as a peak. An amplifier circuit was fabricated, which helped improve sensitivity of the flame photometer. Calibration graphs in the range of 0.05–1.0 mg L−1 and 1.0–20.0 mg L−1 were obtained with a detection limit of 0.02 mg L−1, for both potassium and sodium determination. Relative standard deviations for 11 replicates of injecting of 10 mg L−1 potassium and sodium solutions were 1.69 and 1.79%, respectively. Sample throughput of 120 h−1 was achieved. The proposed method was successfully applied to portland cement, fly ash, admixtures, and water samples validated by the ASTM standard method and certified reference materials of portland cement

Determination of chloride in admixtures and aggregates for cement by a simple flow injection potentiometric system

a b s t r a c t A simple flow injection system using three 3-way solenoid valves as an electric control injection valve and with a simple home-made chloride ion selective electrode based on Ag/AgCl wire as a sensor for determination of water soluble chloride in admixtures and aggregates for cement has been developed. A liquid sample or an extract was injected into a water carrier stream which was then merged with 0.1 M KNO 3 stream and flowed through a flow cell where the solution will be in contact with the sensor, producing a potential change recorded as a peak. A calibration graph in range of 10-100 mg L −1 was obtained with a detection limit of 2 mg L −1 . Relative standard deviations for 7 replicates injecting of 20, 60 and 90 mg L −1 chloride solutions were 1.0, 1.2 and 0.6%, respectively. Sample throughput of 60 h was achieved with the consumption of 1 mL each of electrolyte solution and water carrier. The developed method was validated by the British Standard methods

Development of microwave-assisted sintering of Portland cement raw meal

Typically, using a rotary furnace as a heat generator, a temperature of approximately 1450 °C and a time of 60 min is needed to produce clinker requiring large amounts of energy. Recently, a method of sintering Portland cement by microwave furnace has been developed with the aim to reduce this high consumption of energy in the conventional cement production. In this work, cement raw meal was calcined by a microwave furnace operating at 2.45 GHz with 900 W at 1150 °C at several periods of time but was not completely successful in terms of clinker formation. Therefore, an electric furnace was used at 1300 °C and 1350 °C for 30 min to further heat the material. Chemical compositions of the formed clinker, characterized by XRD, presented C3S, C2S, C3A and C4AF as the main constituents confirming a clinker similar to those of clinker produced by rotary kiln or conventional technique. Loss on ignition and insoluble residue of the resultant clinker were analyzed by chemical analysis and the results were found to pass ASTM C-114. It was found that the raw meal sintering process using a microwave furnace followed by transfer to an electric furnace could reduce not only the temperature by at least 100 °C but also the processing time of the clinker. In addition, there is no grinding cost for clinker preparation in this process. This processing of clinker would decrease energy consumption and carbon dioxide emission to the atmosphere, a major cause of global warming